Development of a mechanical setup for assessing stiffness of the wrist joints with 3 DOF of motion (A037)

Abstract

The objective of this project is to design and develop a fully mechanical contraption for assessing the stiffness of human wrist joints. The previous designs have attached torque motors at each point of rotation and had 2 DOF. The primary aim of this project is to design a new setup with 3 DOF that is inertially balanced at all positions. In order to effectively measure slow and fast perturbation without having the weight of the setup affect the stiffness of the human wrist, this inertially balanced setup is required. Validation tests for static and continuous perturbation in flexion-extension are examined. Pronation-Supination is also examined as the 3rd DOF while Radial-Ulnar deviation are also included in the measurements. Because the dynamics of wrist rotations are dominated by stiffness, understanding wrist rotations requires a thorough characterization of wrist stiffness in multiple degrees of freedom. The only prior measurement of multivariable wrist stiffness was confined to approximately one-seventh of the wrist range of motion (ROM). Here, we present a precise nonlinear characterization of passive wrist joint stiffness over a range three times greater, which covers approximately 70% of the functional ROM of the wrist.